Blocklisting - What it means and what to do about it

A blocklist (previously known as blacklist - see https://www.ncsc.gov.uk/blog-post/terminology-its-not-black-and-white) from an email marketing perspective is a list of domains or IP addresses that have been associated with spam or more serious forms of abuse, such as phishing. If the domain or IP address associated with your email marketing is on a blocklist, then this can result in email messages being blocked temporarily or permanently.

The IP address will typically be associated with the ESP that sends emails on your behalf, but the domains can be associated with several things:

• The sending domain that you use to dispatch email marketing

• Target domains for links in the email – often your website

• Links to other domains that exist on the pages that your email links to

That last one is among the more pervasive reasons that emails can get blocked and blocklisted. One publishing client at e-shot^TM sent an email with a link to one of their advertiser’s websites. In turn, that website linked to another website that had been blocklisted after it had been hacked. That negative association with the third-party website was enough to seriously impact the results of their campaign and led to a temporary blocklist of their sending domain.

Frustratingly, this domain had been flagged in e-shot’s Email Forensics which is used to safeguard against such incidents, but the blocklisting had been missed during the quality assurance phase of sending the campaign. Fortunately, we were able to delist the domain quickly and no lasting damage was done, but this was primarily due to the monitoring in place.

Hidden problem?

Some email marketers continue in blissful ignorance of blocklistings and the damage they can cause. The level of awareness of blocklistings amongst email marketers is quite variable. In their 2019 state of email marketing survey, Litmus reported that 25.7% of survey respondents had encountered emails being blocked. 7.5% reported being blocked several times.

It would be easy to jump to the conclusion that those who were blocklisted were those with shoddy email marketing practices, but the Litmus report found the reverse. It was those with better quality assurance processes; those who were monitoring and checking that reported more blocks and blocklistings.

The likelihood is most email marketers have had campaigns blocked or blocklisted at some point, but they may not be aware of them.

Who holds the blocklists?

There are hundreds of blocklists and most of them operate outside of any legal jurisdiction, but they will often follow a privacy and security centric approach that cares little for your average marketing professional. Most blocklists are maintained by either cyber-security software vendors such as Barracuda or by ISPs, such as Microsoft.

Monitoring blocklists

e-shot^TM monitors and provides real-time reporting to clients on 96 important blocklists. The highly technical nature of this technology means that it is difficult to monitor manually. That’s why we recommend checking your campaign throughout the creation process and again, just before sending using Email Forensics.

What to do if you are blocklisted

Prevention is better than cure, but if something does slip through or a blocklisting occurs because of issues with the contacts the campaign is sent to, remedial action can also be carried out post-campaign.

This will typically involve submitting an unblock request to the relevant blocklist service. This varies in complexity, but the e-shot team can guide you accordingly.

If you find a more serious or permanent blocklisting has occurred, then this may involve some negotiation with the blocklist provider and wider investigation into the cause.

The more serious cases of blocklistings are usually associated with campaigns to unsolicited contacts where a confirmed opt-in record is not evident. Having good data insights and being able to pinpoint specific campaigns and your subscriber sources will speed up the delisting process.

If you do encounter regular blocklistings, then data cleanse and re-engagement with your contacts becomes essential to retain the ability to send email marketing.

e-shot^TM believe it is not a software company’s job to judge the marketing efforts of any of its customers. Our role is to help our customers succeed, to guide them on best practice and in practical terms, help them if they run into issues with blocklists or other email deliverability issues.

You will find more information on best-practice advice in this respect in our Deliverability Webinar.

If you are a customer and you would like more help, then chat to our Customer Success team who will be able to check things and guide you.

For those who do not use, e-shot, we also offer a free healthcheck that will identify blocklistings along with a range of other quality assurance checks to your email campaigns.